Process for reducing peroxide migration in crosslinkable ethylene-based polymer compositions

a technology of ethylene-based polymer compositions and crosslinkable ethylene-based polymer compositions, which is applied in the direction of inorganic insulators, plastic/resin/waxes insulators, cements, etc., can solve the problems of crosslinkable ethylene-based polymer insulation failure or breakdown in an actual service environment, migration of peroxide to the outside or surface, and current compounds suffering from a range of limitations

Active Publication Date: 2017-09-12
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent is about a composition that includes a crosslinkable ethylene-based polymer, a peroxide initiator, and a dielectric fluid. This composition can be used to make medium or high voltage cable insulation. The technical effect of this invention is that it provides a more efficient and effective insulation material for cables that can withstand higher voltage levels.

Problems solved by technology

Such defects are the cause of failure or breakdown of crosslinked ethylene-based polymer insulation in an actual service environment.
However in spite of the continued improvement of XLPE formulations for cable insulation, current compounds suffer from a range of limitations due to additive solubility limitations and the antagonistic interaction of the additives themselves.
The biggest issue with XLPE compositions is the migration of the peroxide to the outside or surface of the polymer pellets during compound storage and / or transport.
Therefore commercial XLPE compositions suffer from significant peroxide migration issues, an effect which increases with time.
XLPE pellets which have migrated peroxide on the surface lead to a number of problems during cable production.
The slippage and irregular feeding of the XLPE composition with migrated peroxide can lead to variation in cable core diameter and increased scrap cable generation.
This is a significant problem for XLPE composition producers and cable manufacturers.
However the use of acrylate copolymers increases significantly the dissipation factor (tan delta) of the polymer composition rendering the copolymer approach ineffective for higher voltage insulations where dissipation factor should be kept as low as possible.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific embodiments

Materials

[0078]The following materials are used in the following examples. The materials are dried or otherwise treated, if at all, as described.

[0079]DFDK 7423NT is LDPE with a density of 0.920 g / cc (measured by ASTM D-792) and a nominal I2 of 2.0 g / 10 min (measured by ASTM D-1238, condition 190 C / 2.16 kg) available from The Dow Chemical Company.

[0080]Dicumyl peroxide (DCP) is available Arkema as LUPEROX™ DC.

[0081]TBM-6 anti-oxidant is 4, 4-Thiobis(2-t-butyl-5-methylphenol) known as LOWINOX™ TBM-6 is available from Great Lakes Chemical.

[0082]Alpha-methyl styrene dimer (AMSD) is a scorch inhibitor available from Nippon Oil and Fats Company.

[0083]SYNESSTIC 5 is an alkylated naphthalene with a kinematic viscosity 100 C (cSt) measured by ASTM D-445 of 5 and available from ExxonMobil Chemical.

[0084]SYNESSTIC 12 is an alkylated naphthalene with a kinematic viscosity 100 C (cSt) measured by ASTM D-445 of 12 and available from ExxonMobil Chemical.

[0085]Procedures and Test Methods

[0086]Comp...

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Abstract

A composition comprising: A. 91.5 to 97.9% of a crosslinkable ethylene-based polymer, e.g., LDPE; B. 1 to 3% of an organic peroxide, e.g., dicumyl peroxide; C. 1 to 5% of a dielectric fluid, e.g., an alkylated naphthalene; and D. 0.1 to 0.5% of a coagent such as AMSD. The compositions exhibit high cure rates without any significant reduction in scorch resistance, heat ageing and electrical performance, and are particularly useful as insulation sheaths for medium and high voltage power cables.

Description

FIELD OF THE INVENTION[0001]This invention relates to crosslinkable, ethylene-based polymer compositions. In one aspect, the invention relates to crosslinkable, ethylene-based compositions comprising a peroxide initiator while in another aspect, the invention relates to such compositions used for making medium and high voltage cable insulation.BACKGROUND OF THE INVENTION[0002]Current state of the art insulation compounds for medium and high voltage cables are based upon low density polyethylene (LDPE) containing about 2 weight percent (wt %) of peroxide. This basic formulation is generally enhanced for commercial use by the addition of a range of additives which includes the following: anti-oxidants, heat stabilizers, scorch retarders, cure boosters, voltage stabilizers and in the case of medium voltage cables, an additive to inhibit water treeing. The final commercial formulation is often a compromise between scorch, cure, heat ageing performance and electrical behavior.[0003]The m...

Claims

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Application Information

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Patent Type & AuthorityPatents(United States)
IPC IPC(8): C08K5/14C08K5/01H01B3/14H01B3/44
CPCC08K5/14C08K5/01H01B3/441C08L23/04C08K2201/014B29B7/007B29B7/38B29B7/726B29B7/90
InventorCREE, STEPHEN H.
OwnerDOW GLOBAL TECH LLC